Satellite gravity and geoid studies reveal the tectonic setting and isostatic state of large-scale basin structures
|Category||Tectonic & Seismotectonic|
|Location||International Geological Congress,oslo 2008|
|Author||Braitenberg, Carla۱; Ebbing, Jِrg۲|
|Holding Date||24 September 2008|
We compare results from a global study of the large-scale basin structures, which are often referred to as cratonic or intra-cratonic basins. Detailed study of satellite derived gravity anomalies, geoid undulations and the isostatic state of these large-scale basin structures show a series of distinctive features: the presence of volcanic material, and a thick sedimentary succession, even with large variations in absolute thickness and aerial extension, and most striking evidence for high-density material in the lower crust and/or upper mantle. Isostatic compensation is achieved for these basins by high-density structures which compensate at least partly for the low-density sedimentary infill, while crustal thickness variations and Moho topography cannot be considered solely as mechanisms of compensation of the sedimentary loading. This is in clear contrast to typical rift type basins, where crustal thinning is governing the isostatic state. Detailed studies from the West Siberian basin and the Eastern Barents Sea basins in the high Arctic, the Michigan basin in North America, the Solimôes, Amazon, Parnaìba and Paranà basins in South America and the Tarim basin in Central Asia imply that the formation of large-scale basins is apparently inked to large-scale lithospheric processes. The global comparison allows us also to test mechanism models, which might be valid for less well-known basins in remote areas, e.g. the Congo basin.